The Indian rainfall data set was derived from 306 almost uniformly distributed stations for which rainfall data are available from 1871. The hilly regions consisting of four meteorological subdivisions of India which are parallel to Himalayan mountain range have not been considered in view of the meagre ... rain-gauge network and low areal representation of a rain-gauge in a hilly area. Two island subdivisions far away from mainland have also not been included. Thus, the contiguous area having network of 306 stations over 30 meteorological subdivisions measures about 2,880,000 sq.km., which is about 90 percent of the total area of the country.

The monthly (January - December) area weighted rainfall series for each of the 30 meteorological subdivisions have been prepared by assigning the district area as the weight for each rain-gauge station in that subdivision. Similarly assigning the subdivision area as the weight to each of the subdivisions in the region, area weighted monthly rainfall series are prepared for Homogeneous regions of India as well as for all India.

The data for the recent period 1991-2003 are preliminary estimates based on the subdivisional means supplied by the India Meteorlogical Department (IMD), which are in turn based on a variable network. However, the IMD data have been rescaled to conform to the long-term means of the respective subdivisions in the IITM-IMR data set. These data will be updated as and when the full set of data for 306 stations becomes available.

The accompanying data as described below may be freely used and redistributed for non-profit and non-commercial research purposes provided IITM is duly acknowledged as the data source. Any redistribution should necessarily include this document.